Hey guys started looking into suspension upgrades for my 86 GT. I am going to do a 88 cradle swap and want to add coil overs front and rear. Just wondering if there is one go to for coilovers that everyone is using?

You can make your own rear coil overs. There are several topics/threads on this forum. Just use the search fonction.
As for the front, you do know that your shock absorbers are separate from the springs?
It's not impossible, but will require quite a bit of fabrication to turn an '84-'87 front suspension into a true coil over setup.

------------------
"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM

Front is the challenge. Pickartd Performance (2P's) builds these. You would need to contact them for details and availability. P-Body motorsports can also help you out. I know he is working on an updated design for coilover suspension in the front and rear. Again, contact (James Brown) and ask about it.

I don’t think there is any specific benefit to having a coilover setup.

Having the shock as an assembly with the spring versus divorced is a packaging-related decision.